1. Field of the Invention
The present invention relates to the fields of disk drives and computer systems. In particular, the present invention relates to controlling power application when hot docking a Small Computer System Interface (SCSI) Single Connector Attachment (SCA) disk drive.
2. Background Information
As more and more microprocessor based servers are employed in various critical or sensitive business or scientific applications, the expectation of their reliability and availability increases in tandem. A particular aspect that is of increasing interest is the availability and reliability of the server's disk drives. In today's servers, it is not uncommon to find a not insignificant number of disk drives storing many gigabytes of data. As a result, hot swappable or hot dockable disk drives have emerged as a high priority feature.
Hot swapping or hot docking refers to the ability to remove a malfunctioning disk drive from the server and reinsert a properly functioning disk drive into the server without having to halt and/or otherwise shut the server down. Excessive power and voltage swings must be prevented when removing the malfunctioning disk drive and reinserting the replacement drive, to prevent disruption to operations and/or physical damages to the neighboring drives. The conventional approach is to employ disk drives having connecting pins that are of uneven lengths. More specifically, special 5 v and 12 v pins having lengths that are longer than associated pins are used to make preliminary electrical contacts with the power supply of the server, thereby stabilizing the power and voltage of the server, before the shorter operational pins would make full electrical contact with the power supply of the server.
An SCA drive by definition has equal length connecting pins. Thus, traditionally SCA drives are not considered to be hot swappable or hot dockable. Since SCA drives, due to other reasons, are a lot more economical than most of the hot dockable drives employed today, it is desirable to be able to hot dock SCA drives.
As will be disclosed in more detail below, the circuitry of the present invention controls power application to a hot docking SCA disk drive, thereby allowing the SCA disk drive to be hot dockable. These and other advantages will be evident to those skilled in art from the detailed descriptions to follow.